1. Field of the Invention
The present invention relates to a recording medium, a method for manufacturing same, and an inkjet recording method using same.
2. Description of the Related Art
An inkjet apparatus has a simple structure, and high-quality image recording can be conducted by inkjet recording performed using the inkjet apparatus. The viscosity of the ink used for inkjet recording is adjusted to a range from about several Pa·s to about 30 Pa·s and the ink is designed to have a surface tension of about 20 mN to about 40 mN/m, so that the ink can be ejected from an inkjet head.
The ink usually includes 50% to 90% by mass ink solvent so as to obtain the ink viscosity within the aforementioned range. Examples of suitable ink solvents include water, organic solvents, oils, and photopolymerizable monomers. From the standpoint of environmental compatibility, water is most often used. Further, a high-boiling solvent such as glycerin is generally used as an ink solvent in order to prevent an ejection nozzle of the inkjet head from being clogged due to drying of the ink solvent.
On the other hand, when a large amount of ink solvent is present on a recording medium where an ink image has been formed, image bleeding and mixing of colors caused by the large amount of ink solvent can easily occur. For this reason a special inkjet paper (see FIG. 5) having on the surface thereof a solvent absorbing layer (ink accommodating layer) that has a thickness of about 20 μm to 30 μm and is capable of absorbing an ink solvent is used as a recording medium, thereby preventing the occurrence of image bleeding and color mixing.
In the case of an aqueous ink using water as the ink solvent, the water penetrates into the base paper during recording, thereby causing paper deformation such as curling. However, where an inkjet special paper 200 has a solvent-absorbing layer 22 on a base paper 21, as shown in FIG. 5, water is prevented from penetrating into the base paper and paper deformation can be inhibited.
In particular, when graphical images with a high image density and a high image surface area ratio are to be formed, the amount of ink per unit surface area on the recording medium increases, and the solvent absorbing layer can hardly prevent the ink solvent from penetrating into the base paper. For this reason, water-resistance paper (for example, laminate paper) that is covered with a resin layer using a polyolefin or the like is typically used (for example, see JP-A Nos. 2005-238829 and 2005-96285).
However, inkjet technology is used not only in the field of office printers and home printers. In recent years, it has found application in the field of commercial printing. In commercial printing, printed sheets are required to have an appearance similar to that of general printing paper, rather than a surface, such as that of a photograph, that completely blocks penetration of ink solvent into base paper. However, the range of properties such as surface gloss, texture and stiffness is limited when a recording medium has a solvent absorption layer with a thickness as large as from 20 μm to 30 μm. Therefore, application of inkjet techniques in commercial printing has been limited, for example, to posters and vouchers, with respect to which the restrictions on surface gloss, texture, stiffness and the like are tolerable
Further, not only is the feel of the printed paper important, but the image is also required to adhere strongly to the paper, which is a recording medium, and be present thereon with good stability as a recorded image. Thus, it is necessary that no defects such as peeling or scratches appear in the image produced, due to, for example, contact with the conveying path in the image formation process.
On the other hand, because the recording medium has such solvent absorbing layer and waterproofing layer, cost thereof rises, and this also becomes the reason for the aforementioned restrictions.
In this respect, a coated white sheet paper suitable for offset and gravure printing has been disclosed, this paper using an engineered delaminated clay and soft calcium carbonate combined at a predetermined ratio in the coating layer having a two-layer configuration (for example, see JP-A No. 2006-9184), and excellent smoothness and bulkiness has been obtained. Further, using delaminated clay of a predetermined mean particle size for decreasing white paper gloss of matte coated paper has been described (for example, see JP-A No. 5-5297).
Furthermore, it has been disclosed that by using delaminated kaolin with a predetermined particle size at a content ratio 90% or more by mass in a pigment coating layer of coated paper for gravure printing, it is possible to improve wettability and increase tone jump or ink mottle (see, for example, Japanese Patent No. 3788508).
However, in the above-described coated white sheet paper and coated paper, the occurrence of image peeling or the like is difficult to avoid and high-quality images are difficult to obtain with good stability. Moreover, the fixation ability of images is insufficient.
From the standpoint of commercial value, it is generally desirable to provide the recording materials with waterpoofness of a high level such that paper deformation, e.g. curling, occurring for example when a large amount of ink solvent is applied to the recording material can be avoided.